We do let Tortilla (our cat) out supervised in the backyard. She is actually very attached to the home and doesn't go far but does like the sunshine. We also leave the blinds up in the back of the house so she can sunbathe and watch the birds, this seems to make her quite content. She tried once to jump our fence (6 foot privacy) but didn't make it. Now we are careful to supervise her, of course if she is being stubborn our puppy will herd her in for us. 
I think it depends on the cat the level of safety outdoors. My husband's stepmother lets hers outside and they have all lived long lives. They do live on a very quiet street, with a two acre lot and her cats always seem to stay close to home. They do have poisonous snakes and other dangerous wildlife but it has not thus far proved to be an issue. My street however is more of a through street for the neighborhood with people often speeding, so I wouldn't feel safe having Tortilla out if she wasn't declawed.
I agree with Irulan, I actually get quite annoyed with roaming animals even though I am an animal nut. The cats scare birds out of my bath, chase them from my tree and sometimes spray my flower bed (yuck smell). The dogs kill our toads in the yard but leave them, poop in the yard and run out in front of me on bike and car!
On the cat puking, Tortilla has not puked once in the two years we have had her. I think this is rare but I grew up with cats (long and short hair) and did not have them puking all the time. Tortilla is medium fur and doesn't have a hairball problem. Although she does shed a ton, get a lint roller!
Amanda
2011 Specialized Epic Comp 29er | Specialized Phenom | "Marie Laveau"
2007 Cannondale Synapse Carbon Road | Selle Italia Lady Gel Flow | "Miranda"
You don't have to be great to get started, but you do have to get started to be great. -Lee J. Colan